1. Field of the Invention
The present invention relates to a heat pump type hot water supply apparatus for heating water by using refrigerant heat and then stocking the hot water thus achieved in a hot-water supply tank.
2. Description of the Related Art
There has been hitherto proposed such a heat pump type hot water apparatus that a heat exchanger for hot water supply heats water by using heat of refrigerant and the hot water thus achieved is stocked in a hot-water supply tank. In general, such a type of hot water supply apparatus is equipped with a heat-pump unit containing a compressor, a heat-pump heat exchanger and a pressure-reducing device, and a hot water unit containing a refrigerant-water heat exchanger for performing the heat exchange between refrigerant and water and a hot-water supply tank for stocking hot water achieved through the heat exchange between refrigerant and water in the refrigerant-water heat exchanger, and the hot water unit and the heat pump unit are connected to each other through a refrigerant pipe.
However, in a case where the heat pump type hot water supply apparatus having the above construction is designed so that the refrigerant pipe through which the hot water unit and the heat pump unit are connected to each other is exposed to the outside, the safety of the heat pump type hot water supply apparatus might be lost if the refrigerant is formed of a refrigerant material containing a large amount of carbon dioxide because the refrigerant pressure of the refrigerant material is higher than that of freon-based refrigerant.
Further, some of heat pump type hot water supply apparatuses as described above have not only a refrigerant-water heat exchanger for hot water supply, but also a refrigerant-water heat exchanger for reheating of hot water or water in a bath tub. In this case, the heat pump unit must be actuated even when it is sufficient to reheat the hot water or water in the bath tub without supplying hot water into the bath tub.
Further, in this type of heat pump hot water supply apparatus, the temperature of hot water at the top portion of the hot-water supply tank rises up, and thus there is used such a method that a hot-water outlet pipe is connected to the top portion of the hot water supply tank to take out hot water at the top portion, the hot water supplied through the hot-water outlet pipe is mixed with water to adjust the temperature of the hot water to a proper value, and then the temperature-adjusted hot water is supplied to users. In this case, if the temperature of the hot water in the hot-water supply tank is high, a large amount of water must be mixed with the hot water, and the mixing of a large amount of water reduces the energy efficiency of the heat pump type hot water supply apparatus.
The present invention has been implemented in view of the foregoing situation, and has an object to provide a heat pump type hot water supply apparatus which can prevent a high-pressure refrigerant pipe from being exposed to the outside to enhance the safety of the apparatus and enhance the energy efficiency of the heat pump type hot water supply apparatus.
In order to attain the above object, according to the present invention, there is provided a heat pump type hot water supply apparatus for heating water by refrigerant heat and stocking the hot water thus achieved, characterized by comprising: a heat pump unit having a refrigerant circuit using natural refrigerant, the refrigerant circuit including a compressor for compressing refrigerant, a heat-pump heat exchanger and a refrigerant-water heat exchanger for performing the heat exchange between refrigerant and water to achieve hot water; a hot water supply unit including a hot water supply tank for stocking the hot water achieved by the refrigerant-water heat exchanger of the heat pump unit and supplying the hot water thus stocked; and a water pipe through which the refrigerant-water heat exchanger of the heat pump unit and the hot water supply tank of the hot water supply unit are connected to each other to circulate hot-water/water between the refrigerant-water heat exchanger and the hot water supply tank.
In the heat pump type hot water supply apparatus of the present invention, the hot water supply unit further includes hot-water joint control means for controlling the joint of hot water supplied from at least two inner portions of the hot water supply tank which are different in hot-water temperature.
In the heat pump type hot water supply apparatus of the present invention, the hot-water joint control means comprises at least two hot water outlet pipes that extend from the hot water supply tank and join each other at one ends thereof and through which the hot water is supplied from the hot water supply tank to the outside thereof, each of at least two hot water outlet pipes being equipped with an opening/closing valve for allowing/intercepting flow of the hot water therethrough, and a controller for controlling the opening/closing operation of the opening/closing valves of at least two hot water outlet pipes.
In the heat pump type hot water supply apparatus of the present invention, the controller controls the opening/closing operation of the opening/closing valves in accordance with the temperature of the hot water in at least one of at least two inner portions of the hot water supply tank so that hot water having a proper temperature is supplied.
In the heat pump type hot water supply apparatus of the present invention, the hot-water joint control means comprises at least two hot water outlet pipes that extend from the hot water supply tank and join each other at one ends thereof and through which the hot water is supplied from the hot water supply tank to the outside thereof, a mixing valve disposed at the joint position of at least two hot water outlet pipes, the mixing valve controlling the joint degree of the hot water supplied through at least two hot water outlet pipes, and a controller for controlling the mixing operation of the mixing valve.
In the heat pump type hot water supply apparatus of the present invention, the controller controls the mixing valve to adjust the mixing degree of the hot water supplied through at least two hot water outlet pipes in accordance with the temperature of the hot water in at least one of at least two inner portions of the hot water supply tank so that hot water having a proper temperature is supplied.
In the heat pump type hot water supply apparatus of the present invention, the mixing valve comprises a wax valve.
In the heat pump type hot water supply apparatus of the present invention, at least two inner portions of the hot water supply tank includes the top portion of the hot water supply tank and an intermediate portion between the top portion and the bottom portion of the hot water supply tank.
In the heat pump type hot water supply apparatus of the present invention, the hot water supply unit further includes a waterxe2x80x94water heat exchanger for performing the heat exchange between the hot water supplied from the hot water supply tank and hot-water/water circulated in a bath tub to reheat the hot-water/water in the bath tub.
In the heat pump type hot water supply apparatus of the present invention, the hot water supply unit includes a mixing control valve for controlling the mixing of tap water and the hot water from the hot water supply tank so that the temperature of the hot water from the hot water supply unit is set to a proper temperature.